source4/dsdb/dns/dns_update.c

   1 /*
   2    Unix SMB/CIFS mplementation.
   3
   4    DNS udpate service
   5
   6    Copyright (C) Andrew Tridgell 2009
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 */
  22
  23 /*
  24   this module auto-creates the named.conf.update file, which tells
  25   bind9 what KRB5 principals it should accept for updates to our zone
  26  */
  27
  28 #include "includes.h"
  29 #include "dsdb/samdb/samdb.h"
  30 #include "auth/auth.h"
  31 #include "smbd/service.h"
  32 #include "lib/events/events.h"
  33 #include "lib/messaging/irpc.h"
  34 #include "lib/ldb/include/ldb_errors.h"
  35 #include "param/param.h"
  36 #include "system/filesys.h"
  37 #include "lib/tevent/tevent.h"
  38
  39 struct dnsupdate_service {
  40         struct task_server *task;
  41         struct auth_session_info *system_session_info;
  42         struct ldb_context *samdb;
  43
  44         struct {
  45                 uint32_t interval;
  46                 struct tevent_timer *te;
  47         } periodic;
  48 };
  49
  50 /*
  51   called every dnsupdate:interval seconds
  52  */
  53 static void dnsupdate_rebuild(struct dnsupdate_service *service)
  54 {
  55         int ret;
  56         struct ldb_result *res;
  57         const char *tmp_path, *path;
  58         int fd, i;
  59         const char *attrs[] = { "sAMAccountName", NULL };
  60         const char *realm = lp_realm(service->task->lp_ctx);
  61         TALLOC_CTX *tmp_ctx = talloc_new(service);
  62         const char *rndc_cmd;
  63
  64         ret = ldb_search(service->samdb, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE,
  65                          attrs, "(&(primaryGroupID=%u)(objectClass=computer))",
  66                          DOMAIN_RID_DCS);
  67         if (ret != LDB_SUCCESS) {
  68                 DEBUG(0,(__location__ ": Unable to find DCs list - %s", ldb_errstring(service->samdb)));
  69                 talloc_free(tmp_ctx);
  70                 return;
  71         }
  72
  73         path = lp_parm_string(service->task->lp_ctx, NULL, "dnsupdate", "path");
  74         if (path == NULL) {
  75                 path = private_path(tmp_ctx, service->task->lp_ctx, "named.conf.update");
  76         }
  77
  78         tmp_path = talloc_asprintf(tmp_ctx, "%s.tmp", path);
  79         if (path == NULL || tmp_path == NULL) {
  80                 DEBUG(0,(__location__ ": Unable to get paths"));
  81                 talloc_free(tmp_ctx);
  82                 return;
  83         }
  84
  85         unlink(tmp_path);
  86         fd = open(tmp_path, O_CREAT|O_TRUNC|O_WRONLY, 0444);
  87         if (fd == -1) {
  88                 DEBUG(1,(__location__ ": Unable to open %s - %s\n", tmp_path, strerror(errno)));
  89                 talloc_free(tmp_ctx);
  90                 return;
  91         }
  92
  93         dprintf(fd, "/* this file is auto-generated - do not edit */\n");
  94         dprintf(fd, "update-policy {\n");
  95         dprintf(fd, "\tgrant %s ms-self * A AAAA;\n", realm);
  96         dprintf(fd, "\tgrant administrator@%s wildcard * A AAAA SRV CNAME TXT;\n", realm);
  97
  98         for (i=0; i<res->count; i++) {
  99                 const char *acctname;
 100                 acctname = ldb_msg_find_attr_as_string(res->msgs[i],
 101                                                        "sAMAccountName", NULL);
 102                 if (!acctname) continue;
 103                 dprintf(fd, "\tgrant %s@%s wildcard * A AAAA SRV CNAME;\n",
 104                         acctname, realm);
 105         }
 106         dprintf(fd, "};\n");
 107         close(fd);
 108
 109         if (file_compare(tmp_path, path) == true) {
 110                 unlink(tmp_path);
 111                 talloc_free(tmp_ctx);
 112                 return;
 113         }
 114
 115         if (rename(tmp_path, path) != 0) {
 116                 DEBUG(0,(__location__ ": Failed to rename %s to %s - %s\n",
 117                          tmp_path, path, strerror(errno)));
 118                 talloc_free(tmp_ctx);
 119                 return;
 120         }
 121
 122         DEBUG(1,("Loaded new DNS update grant rules\n"));
 123
 124         rndc_cmd = lp_parm_string(service->task->lp_ctx, NULL, "dnsupdate", "rndc reload command");
 125         if (!rndc_cmd) {
 126                 rndc_cmd = "/usr/sbin/rndc reload";
 127         }
 128         ret = system(rndc_cmd);
 129         if (ret != 0) {
 130                 DEBUG(0,(__location__ ": Failed rndc reload command: '%s' - %d\n",
 131                          rndc_cmd, ret));
 132         }
 133
 134         talloc_free(tmp_ctx);
 135 }
 136
 137 static NTSTATUS dnsupdate_periodic_schedule(struct dnsupdate_service *service);
 138
 139 /*
 140   called every dnsupdate:interval seconds
 141  */
 142 static void dnsupdate_periodic_handler_te(struct tevent_context *ev, struct tevent_timer *te,
 143                                           struct timeval t, void *ptr)
 144 {
 145         struct dnsupdate_service *service = talloc_get_type(ptr, struct dnsupdate_service);
 146
 147         dnsupdate_rebuild(service);
 148         dnsupdate_periodic_schedule(service);
 149 }
 150
 151
 152 static NTSTATUS dnsupdate_periodic_schedule(struct dnsupdate_service *service)
 153 {
 154         service->periodic.te = tevent_add_timer(service->task->event_ctx, service,
 155                                                 timeval_current_ofs(service->periodic.interval, 0),
 156                                                 dnsupdate_periodic_handler_te, service);
 157         NT_STATUS_HAVE_NO_MEMORY(service->periodic.te);
 158         return NT_STATUS_OK;
 159 }
 160
 161 /*
 162   startup the dns update task
 163 */
 164 static void dnsupdate_task_init(struct task_server *task)
 165 {
 166         NTSTATUS status;
 167         struct dnsupdate_service *service;
 168
 169         if (lp_server_role(task->lp_ctx) != ROLE_DOMAIN_CONTROLLER) {
 170                 /* not useful for non-DC */
 171                 return;
 172         }
 173
 174         task_server_set_title(task, "task[dnsupdate]");
 175
 176         service = talloc_zero(task, struct dnsupdate_service);
 177         if (!service) {
 178                 task_server_terminate(task, "dnsupdate_task_init: out of memory", true);
 179                 return;
 180         }
 181         service->task           = task;
 182         task->private_data      = service;
 183
 184         service->system_session_info = system_session(service->task->lp_ctx);
 185         if (!service->system_session_info) {
 186                 task_server_terminate(task,
 187                                       "dnsupdate: Failed to obtain server credentials\n",
 188                                       true);
 189                 return;
 190         }
 191
 192         service->samdb = samdb_connect(service, service->task->event_ctx, task->lp_ctx,
 193                                        service->system_session_info);
 194         if (!service->samdb) {
 195                 task_server_terminate(task, "dnsupdate: Failed to connect to local samdb\n",
 196                                       true);
 197                 return;
 198         }
 199
 200         service->periodic.interval      = lp_parm_int(task->lp_ctx, NULL,
 201                                                       "dnsupdate", "interval", 60); /* in seconds */
 202
 203         status = dnsupdate_periodic_schedule(service);
 204         if (!NT_STATUS_IS_OK(status)) {
 205                 task_server_terminate(task, talloc_asprintf(task,
 206                                       "dnsupdate: Failed to periodic schedule: %s\n",
 207                                                             nt_errstr(status)), true);
 208                 return;
 209         }
 210
 211         irpc_add_name(task->msg_ctx, "dnsupdate");
 212
 213         /* create the intial file */
 214         dnsupdate_rebuild(service);
 215
 216 }
 217
 218 /*
 219   register ourselves as a available server
 220 */
 221 NTSTATUS server_service_dnsupdate_init(void)
 222 {
 223         return register_server_service("dnsupdate", dnsupdate_task_init);
 224 }